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150               PRACTICAL ORGANIC CHEMISTRY

cooling the flask in cold water. In the course of A-  f hour all
the acid should have been added ; the flask is then replaced on
the water-bath without the air-condenser, and heated for an
hour or more until the reduction is 'complete. This is ascer-
tained by the absence of any smell of . nitrobenzene. The
contents of the flask, on cooling, solidify to a crystalline mass
(a double salt of stannic chloride and aniline hydrochloride)
Whilst still warm, water (100 c.c.) and strong- caustic soda.
solution (140 grams in 200 c.c. water) are added until the
stannic oxide, which is first precipitated, nearly redissolves
and the liquid has a stongly alkaline reaction. If the mixture
begins to boil during the addition of the caustic soda solution
it must be cooled. The aniline, which separates out as a darlc-
coloured oil, is distilled in steam. The apparatus is shown in
Fig. 68, p. 107. The flask containing the aniline is gently
heated on the sand-bath, and steam is passed in from the tin
bottle. It is advisable to heat the aniline mixture on the
water-bath before steam is admitted, as otherwise a largfe
quantity of water condenses in the flask. On distillation,
aniline and water collect in the receiver, the former as a colour-
less oil. When the distillate, as it comes over, appears clea.r
instead of milky, the distillation is stopped. The oil is no^v
extracted from the distillate by shaking up the liquid in n
separating-funnel three times with small quantities (30 c.c.) ox
chloroform. The chloroform solution, separated as far as possible
from water, is further dehydrated by adding a little solid potas-
sium carbonate. The clear liquid is decanted into a distilling- -
flask, the flask rinsed with a little=**%hloroform, and the
chloroform removed by distillation until the temperature
reaches 100, when the receiver is changed. Aniline distils rtt
182  iS3,andhas usually a faint amber colour. Yield, abou.1
30 grains.

2C0HaN02 + sSn -h I2HC1 = 2C0H5NH2 + 3.SnCl4 + 4H2O
Properties.  Colourless, highly refractive liquid, which soon
darkens in colour ; b. p. 183 ; sp. gr. 1*0265 at I5-
\                            Reactions.  T. Add a drop of the oil to a solution of bleacli-
ing powder or sodium hypochlorite. An intense violet colour n.-
f                         tion is produced, which gradually fades.
**    |J                     2. Heat a drop of the oil with a few drops of chloroform, and